“At that time, I had no idea I would become part of this,” she said, looking around the site's learning center, which opened in September.

Black retired April 29 from the National Park Service, which enlisted her in 2004 to help shape the memorial.

The national park commemorates the 40 passengers and crew of United Flight 93 who gave their lives to thwart a terrorist attack on the nation's capital. The passengers averted the attack by overtaking the terrorists, who crashed the jetliner near Shanksville.

Black, an Illinois native, worked at Colonial Williamsburg before arriving in Somerset County. County officials, familiar with her work as a curator at the historical center, sought her help in caring for the tributes that began appearing near the crash site almost from the first day.

“Honestly, many of us thought people would stop coming. ... They kept coming,” Black said.

“They (county officials) knew the (mementos) could be important and needed to be saved. I give them credit,” she said.

Black recalls many meetings and conference calls with planners and family members as work on the site progressed.

“There was a lot of discussion about what that place should be and how we were going to get there. We wanted to do it with consensus,” she said.

She said Joanne Hanley, the site's first superintendent, was instrumental in standing up for that process to make it an inclusive plan from the beginning. The memorial was dedicated Sept. 10, 2011.

“There is a great satisfaction that we did it right, without overdoing it. It's simple. It accommodates large crowds of people. But it also focuses on the crash site. The tributes are not as important as the 40 passengers and crew. That focus is still the primary reason why the memorial was built,” Black said.

“It's that story of what they did and what they chose to do that's important. I hope that people feel we did that justice.”

That perception of the memorial's primary role is among the special qualities Black brought to its creation, said Stephen Clark, superintendent of the five National Parks of Western Pennsylvania.

“What I appreciate is Barbara's absolute dedication to the 40 men and women on that airplane,” he said.

She possesses a “tremendous amount of knowledge” about their stories and has served as a mentor as he adjusted to the role he assumed in 2015.

Black was a “prime architect” of the photos and tributes selected for and the layout of the site's visitor center, he said.

“Without Barbara Black's contributions, I don't think we would enjoy the success that exhibit has achieved,” Clark said.

He credited her leadership following a 2014 fire that damaged the staff's workspace and destroyed artifacts stored on-site.